Re: how can one use mathematica get the approximate derivative of {x,y} data points?

*To*: mathgroup at smc.vnet.net*Subject*: [mg124235] Re: how can one use mathematica get the approximate derivative of {x,y} data points?*From*: "Nasser M. Abbasi" <nma at 12000.org>*Date*: Sat, 14 Jan 2012 17:05:54 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

On 1/14/2012 1:55 AM, Michael B. Heaney wrote: > Hi, > > I have a set of {x,y} data points: > > {{0.03512, -0.5}, {0.0351181, -0.499}, ... {-0.113972, 0.699}, {-0.115072, > 0.7}} > > These data points look like a function y=f(x) when plotted on the x-y axes. > However, I do not know what the function f(x) is. But I need to get the > approximate derivative df/dx, as another set of data points. How can one > use Mathematica to do this? > > Thanks, > > Michael > > -- one way: ?Fit data = {{0.03512, -0.5}, {0.0351181, -0.499}, {-0.113972,0.699}, {-0.115072, 0.7}} f = Fit[data, {1, x, x^2}, x]; D[f, x] --Nasser